Ti₃C₂T_x MXene-Assisted CuBO₂ Hole Transport Layer for High-Performance Ultraviolet Photodetectors

The efficient separation and extraction of holes can be attributed to the favorable properties possessed by the hole transport layer (HTL). Herein, a novel solution-processable hybrid HTL based on CuBO2 and Ti3C2Tx MXene (CuBO2@MXene) is developed to enhance the performance of ultraviolet photodetectors (UV PDs). By optimizing the ratio of Ti3C2Tx MXene to CuBO2, the optimized responsivity and detectivity of the UV PDs based on the composite HTL have achieved 184 mA W-1 and 2.88 x 10(13) cm Hz(1/2) W-1 in self-powered mode, respectively, and even up to 3.25 x 10(4) mA W-1 at -1.5 V. This significant improvement in device performance can be attributed to the interlaced architecture of CuBO2@MXene, which ameliorates hole mobility and charge extraction capability while reducing the trap state density of the HTL. The built-in electric field of the TiO2/CuBO2 heterojunction is strengthened by the incorporation of Ti3C2Tx MXene, thereby significantly reinforcing the photovoltaic effect. Moreover, the lower thermal conductivity of CuBO2@MXene suppresses its pyroelectric effect, weakening the blocking effect of the thermoelectric potential on hole transport and ultimately leading to a remarkable boost in the output current. These results indicate the promising potential of the hybrid CuBO2@MXene HTL for constructing high-performance optoelectronic devices.